Dyspnea or shortness of breath is a normal manifestation of heavy exertion, but it can also be caused by different underlying diseases, therefore understanding the etiology, pathophysiology and differential diagnosis of dyspnea is important in the diagnosis of serious underlying clinical conditions. In this article, the etiology, pathophysiology and differential diagnosis of dyspnea will be discussed in detail.

00:00
I’m just going to describe a little bit
about how we might use these tests in reallife.
00:05
So, for example, we have a patient who presents
in outpatients with breathlessness. They’vebeen breathless for a few weeks on exertion.
The question is: what’s the disease that’scausing it? Well, firstly, we do a full blood
count. Are they anaemic? We must make surethey’re not anaemic as that’s a good cause
of dyspnoea and is easy to discount by a fullblood count. If they have a lung disease causing
breathlessness, then their physiology willbe abnormal. So we do a spirometry, lung volumes
and we do a transfer factor as well. And thatwill fully evaluate whether the lungs might
be contributing towards their dyspnoea.
00:42
A chest x-ray is also done because, if they
have any pleural interstitial lung diseases,they should have an abnormal chest x-ray.
For airways diseases such as asthma and COPD,the x-ray will look fairly normal but, if
they have any infiltration in the lung dueto interstitial lung disease such as pulmonary
fibrosis, it should be visible on a chestx-ray.
01:04
And the last thing we need to think about
is: could this be a cardiac problem? And wemight want to do echocardiograms, an ECG,
a measurement of the brain natriuretic peptidelevel in the blood, all of which will identify
patients who have cardiac-valve problems orcardiac failure, issues which might be making
them breathless.
01:21
And when we get the results of those tests,
it might dictate what we do next.
01:25
So, for example, if you have somebody with
abnormal lung function and it shows an obstructivespirometry, then that suggests they could
have asthma or COPD. And that might be anadequate enough investigation to identify
what the problem might be.
01:37
If it’s restrictive spirometry, then you
have to think about interstitial lung diseaseor chest-wall problems as the cause of their
breathlessness. And that may require furtherinvestigation.
01:48
If they have a fall in their transfer factor,
then that’s actually a very important observationbecause there are only really two or three
major causes for that. One is emphysema butthey should have obstructive lung function
with that as well. Two is interstitial lungdisease. And the third would be pulmonary
emboli or pulmonary hypertension. So pulmonaryvascular disease of some description.
02:09
If the x-ray is abnormal, then you really
need to get more information about what thatabnormality might be due to. If it’s breathlessness
that’s the problem, then we’re thinkingabout pleural disease which will require an
ultrasound or a CT scan to assess in moredetail. If it shows interstitial lung disease,
then a CT scan is absolutely necessary toidentify what’s going on in more detail.
02:28
So this will lead onto our next set of investigations,
obstructive spirometry: is it reversible orirreversible obstruction? And that will dictate
whether the patient has asthma or COPD toa certain extent. If it’s restrictive spirometry,
you need a CT scan to assess the lung parenchymain more detail. The same if you suspect potential
interstitial lung disease because of the chestx-ray changes. And if there’s a low transfer
factor, you do need that CT scan to look forinterstitial lung disease but also you might
need to think about the pulmonary vesselsand do a CT pulmonary angiogram to assess
those in more detail and potentially do anechocardiogram to make sure they don’t have
pulmonary hypertension.
03:05
Now, that’s somebody presenting with dyspnoea
– shortness of breath – in outpatients.
03:11
If you have somebody who’s got lung cancer,
it’s actually a very different scenarioand a very different set of tests become important.
03:17
So somebody presents: mass on the chest x-ray,
they’ve coughed a bit of blood or somethingalong those lines, they make you suspect they
may have lung cancer. Actually they’ve hadtheir chest x-ray. The next test is – there’s
a mass, we need to define that in more detail.
03:32
Let’s do a CT scan to get a three-dimensional
vision of that mass to see exactly where itis in the lung, what tissues it might adjoining
to. And in addition, we may want to stagethe patient to see whether they have liver
or adrenal involvement, metastases perhapsfrom that original lung cancer.
03:52
We do some blood tests. And the reason why
we do those is that, again, that actuallyhelps identify patients who may have metastases
because the alkaline phosphatase will be raisedwith bone metastases and with liver metastases.
And we need to know about calcium, U&amp;Es becausethere are complications of cancer that might
affect those electrolytes.
04:09
And then actually the most important test
will be a biopsy. So once you’ve done theCT scan, the next question is: which biopsy
modality you will use? That would be dictatedby the anatomy that you have defined using
the CT scan. And you’ll do a biopsy andget the histological results and that will
then dictate the treatment. And further testsmight be required to see whether that treatment
is suitable.
04:35
So, for example, if somebody has got a lung
mass, it turns out to be a cancer, it turnsout to be a localised cancer but they have
background COPD making them short of breathon exertion. We may want to resect that cancer
but the worry here is that that’ll makethem more breathless because, to resect the
cancer, we’re going to have to remove alarge amount of lung. So you measure their
lung function and get a feel for whether theycould cope with that lung resection without
ending up in respiratory failure.
05:01
And so on. We might do tests regarding kidney
function to make sure they can cope with thechemotherapy.
05:08
So to summarise this lecture:Diagnostic tests have to be used in a targeted
way to answer specific clinical questionswhen you’re assessing the patient. And the
interpretation of those tests has to takeinto account the clinical context because
the interpretation will be inaccurate withoutdoing that.
05:24
Most patients presenting with suspected lung
disease can be actually fully assessed usingsimple lung-function tests such as a peak
flow, spirometry and a chest x-ray.
05:33
Lung function is actually vital for monitoring
chronic lung disease. So those patients whohave chronic lung impairment need monitoring
over time to see whether that impairment isstaying stable or deteriorating. And that’s
the role of lung-function testing. Mainlyspirometry but not just spirometry, occasionally
transfer factor as well.
05:57
More complex diseases do require more complex
investigations with more detailed lung-functiontesting – such as the transfer factor and
the lung volumes and, potentially a CT scan.
06:07
For some lung diseases – mainly lung cancer
– obtaining histology is vital and essentialto actually confirm the disease and to guide
therapy. And nowadays we have a multitudeof different methods for obtaining histology
from suspected lung cancer patients whichallows us to do this in the vast majority
of patients safely and quickly.
06:27
And thank you for listening.

About the Lecture

The lecture Chronic Dyspnoea and Cancer – Lung Disease by Jeremy Brown, PhD is from the course Introduction to the Respiratory System.

Included Quiz Questions

Which of the following is not an important advantage of CT scan over a chest X ray?

The patient lies down for a CT scan and stands up for a chest X ray.

Defines mediastinal anatomy.

Can identify pulmonary emboli.

Defines interstitial lung disease.

A 20 year old pale female patient comes with presenting complaint of only shortness of breath.What is your first investigation of choice?

Hb estimation.

Complete blood picture.

Chest X-ray.

CT scan.

ECG.

Which of the following diseases result in a fairly normal chest X-ray?

Asthma.

Sarcoidosis.

Cystic fibrosis.

Tuberculosis.

Pneumonia.

Obstructive spirometry results is seen in which disease?

Emphysema.

Pneumonia.

Tuberculosis.

Sarcoidosis.

Cystic fibrosis.

Author of lecture Chronic Dyspnoea and Cancer – Lung Disease

Jeremy Brown, PhD

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